overburden conveyor bridge combination

overburden conveyor bridge combination

Overburden conveyor bridges were developed for East Germanys saxon and lusatian brown coal or lignite mining areas. There layers of lignite and overburden are horizontally and rarely disturbed. Under these geological conditions intoduction of overburden conveyor bridges in 1924 meant a leap in economy of overburden handling. They are used in combination with up to three bucket chain excavators. The bridge and excavator combination is operated in a kind of strip mining regime. It is running on railway tracks along a trench, removing overburden from the lignite deposit at one side and dumping the spoil at the opposite, mined out site. Turning the upperworks of the excavators together with the bucket chain around their vertical axis allows adjustment of the bucket chain to the excavation progress. Once a 10 m strip of overburden has been removed, the railway tracks are shiftet sideways.
Up to the year 1945 25 conveyor bridges of various designs had been built for Saxon and Lustian lignite mines. Right after the end of WW II some of them were dismantled and transported into the Soviet Union, where they were reassembled and put back into operation at suitable locations. Initially, conveyor bridges were custom built for each mine. After WW II however, development in East Germany shifted towards standardized designs. In the year 1983 15 conveyor bridges were in use in East German lignite mines, all but three standard types. After the merger in 1990, the number of lignite mines decreased considerably resulting in scrapping of many conveyor bridges.
The latest and biggest conveyor bridge is the the F60 type, designed to remove up to 60 m deep layers of overburden. Between the two supports the bridge is 270 metres wide. Both supports are running on railroad tracks. The extension arm for dumping spoil is another 170 metres long. Its service weight is 13,150 metric tons. In order to move around a mine during operation, the lenghth of the bridge can be can be adjusted by ± 15 metres, it can also pivot around the support at the excavation side. It is connected with two Es 3150 or Es 3750 type bucket chain excavators. By the addition of a third bucket chain excavator and an 150 m long auxiliary connecting bridge even deeper layers of overburden can be removed. The combination of one F60 type conveyor bridge and two excavators moves at a speed of 5 - 10 metres/min along the tracks.
Even in East Germanys lignite mining areas, conveyor bridges and their attendant bucket chain excavators are gradually being replaced by combinations of bucket wheel excavators and spreaders, which are running on crawlers and therefore more flexible in operation.
The asset is scripted, allowing movement of the conveyor bridge combination along the tracks as well as the bucket chains to be be turned on and off in Surveyor.

Author: K. Bernhard, U. Nagel, E. Schueler

overburden conveyor bridge combination
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